1. Program 1.The standard cosmological model 2.The observed universe 3.Inflation. Neutrinos in cosmology

2. The flatness problem (I) Rewrite Friedmann eq. as Spatial flatness

3. The flatness problem (II) unstable How our universe can be so flat today ?

4. The horizon problem t_0 t_LS Acausal volumes in our present Hubble volume How can be the CMB so uniform with no previous contact ?

5. Inflation Period with Simplest example:(cosm. ct.) Solves flatness problem

6. Inflation Solves homogeneity problem physical scale horizon expansion scale

7. Inflation models Inflaton field evolving slowly in potential INFLATION Inflaton fluctuations produce perturbations Adiabatic (equal entropy per particle) Almost scale invariant (equal amplitude for all wavelengths)

8. cosmology and neutrinos

9. Impact of cosmology on neutrino properties Big Bang Nucleosynthesis Cosmic Microwave Background Large Scale Structure … - Complementary to properties obtained in solar/atmospheric/laboratory exps - is a “Cicerone” of the universe; it plays or may play a role in almost all epochs of the universe

10. in the early universe Cicerone

11. Expanding universe Rate of expansion Luminosity distances

12. Neutrinos in thermal equilibrium (No chemical potential) Interaction rate Weak interactions Number densityEquilibrium distribution Equilibrium when

13. Neutrino decoupling (Exactly the reason why we observe photon black body today) after decoupling density dilutes because both and keep form rates (provided m<<T)

14. Neutrino “temperature” Properties of CNB can be obtained from CMB From entropy cons. relic neutrino background (CNB)

15. Big Bang Nucleosynthesis (BBN) Production of primordial nuclei - Helium mass-fraction - Deuterium and other light elements number-fraction … From PDG 2006

16. BBN Light element production depends on number neutrinos Does not depend on mass provided (what it is important is the expansion rate) Parameterize deviations from In fact, N_eff takes into account other possible light fermions or bosons, even if not fully in thermal equilibrium with the rest (neutrino decoupling near e+e- annih.)

17. BBN limits on neutrinos Attitude has changed since baryon density is deduced from CMB observations Tension between D and 4He, with 4He less in agreement with CMB Probably 4He systematics Limits on Neff are “author dependent” BBN may also probe non-standard interactions of neutrinos Review:Sarkar, hep-ph/9602260 Evidence of cosmol. nus

18. BBN NOT in crisis

19. BBN and asymmetries Possibility not as constrained as for charged particles Introduce general distribution with chemical potentials 1.

20. BBN and asymmetries 2. In principle, good bounds for nu_e and not as good for nu_mu and nu_tau BUT, take into account mixing/oscillations (Use density matrices to describe evolution) Tendency to flavor equilibrium

21. Flavor evolution in BBN epoch Dolgov et al hep-ph/0201287 Serpico & Raffelt astro-ph/0506162 Updated bound Consequence: standard expectations on neutrino density OK Preferred solution

22. in the late universe Cicerone

23. Standard Cosmological Model

24. Cosmological Observations CMB,LSS,SNIa Ly-alpha, lensing,…

25. Standard Cosmological Model

26. DM neutrinos The bulk of the cosmological dark matter has to be cold. Neutrinos have to be subdominant. OK with masses we have measured (excluding highly degenerate masses) cf. Structure formation lead by NR matter, impact of nus on structure formation? 1. 2. move at v=c

27. Structure formation Graph from Raffelt

28. Small scales affected Evolution equation at small scales (& other assumptions) (Notice Small f_nu, MD univ. Neutrino free-streaming suppreses growth of (small scale) structures Expect change at scales smaller than horizon when nu become NR Solution )

29. Power spectrum Lesgourgues, Pastor hep-astro/0603494

30. Power spectrum From Strumia & Vissani hep-ph/0606054

31. Neutrino mass and Cosmic Microwave Background Mass effect in CMB Massive nu goes from R to NR : *** R-M equality Change in expansion rate history Time variation of potentials in RD vs MD No big effects (not as large as LLS) but CMB important when doing a complete fit to all data

32. Neutrino-mass limits Fogli et al hep-ph/0608060 Many authors using different inputs and different priors Absolute mass scale

33. N_effective of neutrinos (radiation) Hannestad astro-ph/0510582 Neff limited by CMB+LSS+… Change in expansion history Radiation smoothes small scale structure Generalization to thermal relics Hannestad & Raffelt astro-ph/0312154 CNB “detected”

34. Caveats Most bounds in standard minimal in fact Care with degeneracies degeneracy m_nu and w broken by BAO Hannestad astro-ph/0505551 Minimal standard model (standard neutrinos) Experimental systematics (Remember 4He) Bias luminous/dark Kristiansen et al astro-ph/0611761 Bias-free limit M=Mixed

35. Future Lesgourgues, Pastor hep-astro/0603494

36. Neutrinos in the very early universe Early universe, Late universe Neutrinos in the very late universe Problems of GUTS for baryogenesis Leptogenesis can generate B-asymmetry - Mass Varying Neutrinos - nu condensate Sakharov conditions Decays of heavy Majoranas of see-saw. Relation to nu mass and mixing phases Scale of Dark Energy might be nu mass

37. Conclusion plays an active role in cosmology properties constrained by cosmology (complementary to other type of constraints)